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May 31, 2013 Oklahoma City Traffic/Chaser Debacle

I generally stay away from opinion posts in this blog, but the events that transpired yesterday deserve attention. First, I think that it needs to be pointed out that chasers and spotters provide invaluable information to the National Weather Service in the form of ground truth. This is a concept that most of the general public (and even some meteorologists) on the East Coast do not fully understand. Without these folks burning their personal gas, warning lead times could be substantially different in some cases. With that said, there are quite a few amateurs out there that know just enough to find a storm and get themselves (and potentially others) killed. These people do not have a handle on basic storm structure and thus do not know how to attack a storm a properly. There are also the experienced guys that know better, but still conduct storm intercepts in an unsafe manner to get their video on CNN. Both of these groups are ruining what used to be a prestigious hobby. Now the million dollar question is what do we do about this problem on the chaser side of the things? It is a tricky question, but I believe that it is going to come down to law enforcement cracking down on obvious storm chasers breaking minor laws (slightly speeding, etc). Is it right? No, but I really do think that this is what is going to end up happening. Then you have the other side of spectrum that contributed to the traffic mess … broadcast meteorologists. Some of these broadcast meteorologists are completely incompetent and they simply have no business on television … much less in a high risk area such as Oklahoma. We are asking for a disaster when we have people, such as Mike Morgan at KFOR, that are telling people to attempt to drive away from a tornado after warnings are out. Keep in mind that this goes against pretty much every tornado/severe weather safety checklist. If you are going to leave, do so well before the storms fire (we are talking 10am). How these people are allowed to stay on the air with a NWA seal is beyond me. Put bluntly, they are an embarrassment to the profession. Broadcast meteorologists need to be held accountable for spewing such garbage, before a large number of people get killed because of inaccurate safety information. If an air traffic controller goes against protocol and puts the public’s safety in jeopardy then they are reprimanded. This should be no different for broadcast meteorologists during severe weather. I would love to see the operational meteorological community as a whole step up and do what needs to be done … hold these incompetent meteorologists accountable.

thunderman

thunderman

 

Recap: Tornadoes in New York, May 29th, 2013

Two tornadoes (an EF-2 and an EF-1) touched down in eastern New York on Wednesday, both around 7:00 p.m., according to the National Weather Service (NWS). The stronger tornado, an EF-2, had winds of up to 125 MPH and caused damage along a relatively wide and long path. The tornado width was estimated at 1 mile wide with a track length of 17 miles from Florida to Rotterdam. The second tornado formed just to the southwest of the EF-2 tornado, around the same time. It was a weaker and shorter-lived tornado, but was associated with the same powerful squall line that was moving east-southeast across New York. An upper level shortwave disturbance passed across New York state on Wednesday. Daytime heating across the state helped destabilize the atmosphere. Veering winds aloft created an environment that was conducive for the formation of tornadoes. I was actually chasing the EF-2 tornado, but was too far west to catch up to it. Heavy rain, flash flooding and traffic didn't help matters. As I drove into the Rotterdam area along I-90, I noticed cars parked under overpasses. While they may have not witnessed the tornado, I'm sure they experienced strong winds and may have been aware of the Tornado Warning. Personally, I did not see a lot of damage, but the tracks of the tornadoes were mainly south of I-90, which was my route of travel. PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE ALBANY NY 1209 PM EDT FRI MAY 31 2013 ...PUBLIC INFORMATION STATEMENT... TORNADO TOUCHDOWN IN MONTGOMERY AND SCHENECTADY COUNTIES ON WEDNESDAY MAY 29 2013. LOCATION... BEGAN IN FLORIDA IN MONTGOMERY COUNTY NEW YORK TO ROTTERDAM IN SCHENECTADY COUNTY NEW YORK. DATE...05/29/2013. ESTIMATED TIME...647-700 PM. MAXIMUM EF SCALE RATING...EF-2. ESTIMATED MAXIMUM WIND SPEED...125 MPH. ESTIMATED PATH WIDTH...1 MILE WIDE. PATH LENGTH...17 MILES. BEGINNING LAT/LON...42.8457/-74.2034 ENDING LAT/LON...42.8042/-74.0208 * FATALITIES...NONE. * INJURIES...1. * THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO CHANGE PENDING FINAL REVIEW OF THE EVENT AND PUBLICATION IN NWS STORM DATA. SUMMARY...PATH WIDTH WAS CONSISTENT ALONG THE ENTIRE PATH LENGTH. MAXIMUM DAMAGE INCLUDED ROOFS TORN OFF OF MULTIPLE STRUCTURES AND HIGH TENSION POWER LINE TOWERS TOPPLED. LARGE NUMBER OF HARD AND SOFT WOOD TREES WERE EITHER TOPPLED...UPROOTED AND OR SHEARED. WIDESPREAD POWER OUTAGES OCCURRED AS WELL. ****************************************************** PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE ALBANY NY 1241 PM EDT FRI MAY 31 2013 ...PUBLIC INFORMATION STATEMENT... TORNADO TOUCHDOWN IN SCHOHARIE COUNTY ON WEDNESDAY MAY 29 2013. LOCATION... SUMMIT AND EAST JEFFERSON IN SCHOHARIE COUNTY NEW YORK. DATE...05/29/2013. ESTIMATED TIME...657 PM TO 702 PM. MAXIMUM EF SCALE RATING...EF-1. ESTIMATED MAXIMUM WIND SPEED...100 MPH. ESTIMATED PATH WIDTH...200 YARDS. PATH LENGTH...2 MILES. BEGINNING LAT/LON...42.515196/-74.554181 ENDING LAT/LON...42.522471/-74.578385 * FATALITIES...NONE. * INJURIES...NONE. * THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO CHANGE PENDING FINAL REVIEW OF THE EVENT AND PUBLICATION IN NWS STORM DATA. SUMMARY...BRIEF TOUCHDOWN ALONG RIDGE LINE SEEN FROM JUNCTURE OF DUTCH HILL ROAD AND WHARTON HOLLOW ROAD. DOZENS OF SOFT AND HARD WOOD TREES FALLEN IN DIFFERENT DIRECTIONS AND SHEARED OFF. ALSO TREES DOWN IN DIFFERENT DIRECTIONS ALONG ENID ROAD AND PERAGLIA ROAD. Here's a look at radar imagery at 7:00 p.m. when both tornadoes were on the ground: Notice overlap of strong bulk wind shear and MUCAPE leading up to the touchdowns: Here's a look at storm reports from across the area: Here are the tornado tracks to date (2013) in the region: Here's a look at my closest pass to the EF-2 tornado, which was basically at the time that it was reported to have lifted off the ground:

Quincy

Quincy

 

Severe WX Outlook, Northeast: Wednesday, May 29th

As a warm front lifts into the Northeastern United States on Wednesday, a warmer, more humid air-mass floods into the Northeast. Some thunderstorm development is forecast and some of those storms may be capable of reaching severe limits, particularly across portions of New York and west-central New England. Low threat (Conditions are somewhat favorable for severe thunderstorms) Interior New England, New York, northwestern New Jersey and norther Pennsylvania: As a warm front clears, an increasingly unstable air-mass overapreads the area, along with increasing dew-points. Once lingering showers, patchy fog and drizzle clear, some daytime heating will begin to fuel the atmosphere. The severe thunderstorm threat relies on a few factors. Although daytime heating is important, it should be noted that bulk wind shear values are forecast to be low to moderate, with the strongest helicity displaced northeast into central and northern New England. A line or broken lines of thunderstorms are expected to develop along a trough during the afternoon. The focus is on central and eastern New York, as well as western Massachusetts and southern Vermont. This area has a fair amount of overlap with respect to wind shear, instability, helicity and proximity to a shortwave passing near the Canadian-United States border. MLCAPE and lifted index values are somewhat supportive of severe thunderstorms, especially assuming there is a fair amount of sunshine to promote destabilization. It is also in this region that both the ARW and NMM model forecast reflectivities indicate a relatively strong squall line dropping southeast between about 5 p.m. and 9 p.m. local time. The threat appears to be mainly strong winds, but isolated hail is another possibility. Although the tornado threat is low, should wind shear coincide enough with higher helicity values, there could be a spin up or two. This area is being monitored and may be upgraded to a moderate threat of severe thunderstorms, should model guidance trends continue. Marginal threat (Conditions are marginally favorable for severe thunderstorms) Elsewhere in green: A few scattered showers and thunderstorms are possible across the region, as far south as the middle Appalachians. Across the coastal plain of New England, decaying thunderstorms could hold together as they approach Interstate 95. Threat definitions...(Severe thunderstorm = wind gusts to 58 MPH and/or >1" hail) Marginal: Conditions are marginally favorable for severe thunderstorms. Low: Conditions are somewhat favorable for severe thunderstorms. Moderate: Conditions are moderately favorable for severe thunderstorms. High: Conditions are very favorable for severe thunderstorms. Extreme: Conditions are extremely favorable and dangerous thunderstorms are likely. *Disclaimer* The intent here is somewhat different than SPC severe weather outlooks. The green, yellow, etc. shadings do not directly correlate between SPC and my own outlooks. I'm still getting a feel for these outlooks, but I imagine that in more impressive severe setups, I will use red and orange colors a bit more generously than SPC might. Also, green colors on my maps indicate a marginal severe weather threat, while on SPC it corresponds to a general thunderstorm (not necessarily severe) threat.

Quincy

Quincy

 

Severe WX Outlook, Mid-Atl.: Wednesday, May 15th

As a warm front lifts into the Northeastern United States on Wednesday, some thunderstorm development is forecast and some of those storms may be capable of reaching severe limits. Low threat (Conditions are somewhat favorable for severe thunderstorms) Central Pennsylvania and portions of Maryland: A warm front is expected to lift into the Northeast on Wednesday. The focus is across the warm sector where some strong wind shear combines with surface/low-level instability to enhance the severe thunderstorm threat. The strongest wind shear and helicity values are projected to move across New York and New England, but there may be enough overlap across portions of the mid-Atlantic states to initiate some severe thunderstorms. The threats at this time look to be for damaging winds and isolated tornadoes. This is heavily dependent on timing and the ability of enough daytime heating to steepen lapse rates. The 15z SREF was showing an area of 1000-2000 J/kg MLCAPE across southern Pennsylvania during Wednesday afternoon. Marginal threat (Conditions are marginally favorable for severe thunderstorms) Elsewhere in green: Although a large area is outlined in green, no organized area of severe thunderstorms is expected here. However, there is marginal atmospheric support for a few damaging wind gusts. Threat definitions...(Severe thunderstorm = wind gusts to 58 MPH and/or >1" hail) Marginal: Conditions are marginally favorable for severe thunderstorms. Low: Conditions are somewhat favorable for severe thunderstorms. Moderate: Conditions are moderately favorable for severe thunderstorms. High: Conditions are very favorable for severe thunderstorms. Extreme: Conditions are extremely favorable and dangerous thunderstorms are likely. *Disclaimer* The intent here is somewhat different than SPC severe weather outlooks. The green, yellow, etc. shadings do not directly correlate between SPC and my own outlooks. I'm still getting a feel for these outlooks, but I imagine that in more impressive severe setups, I will use red and orange colors a bit more generously than SPC might. Also, green colors on my maps indicate a marginal severe weather threat, while on SPC it corresponds to a general thunderstorm (not necessarily severe) threat.

Quincy

Quincy

 

Recap: Tornado in Massachusetts, May 9th, 2013

The National Weather Service (NWS) reported that an EF-0 tornado touched down in eastern Massachusetts Thursday afternoon, shortly after 4:30 p.m. An upper level low lifted northward through New England on Thursday. An unseasonably cold air mass was in place, resulting in cold temperatures aloft. It was the combination of low Lifted Condensation Levels (LCL's) and moderate wind shear aloft that helped create an environment that was marginally supportive of tornado development. It is possible that a land-sea interaction with winds off of the nearby ocean may have played a role in spawning this tornado. The NWS reported that it was a case of a cold air funnel. The tornado touched down in Stoughton, M.A. in Norfolk County and stayed on the ground for 0.25 miles. The tornado was a strong EF-0 with maximum sustained winds of 85 MPH. Damage was minimal, but a local car dealership reported seeing the tornado and had some vehicles blown around by the winds. Looking back at historical tornadoes in the Northeastern United States, the helicity values and amounts of instability in place on Thursday were relatively low compared to prior tornadic events. However, it was the low LCL heights and moderate wind shear that did elevate the tornado potential somewhat. On a scale of 0-5, 0 being unfavorable and 5 being highly favorable for tornadoes (based on local climatology), the environment yielded a value of 1.9. A note that a 2.5 value would be equal to the mean of past tornadoes. PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE TAUNTON MA 158 PM EDT FRI MAY 10 2013 ..TORNADO CONFIRMED IN STOUGHTON IN NORFOLK COUNTY MA LOCATION... STOUGHTON IN NORFOLK COUNTY MA DATE...MAY 9 2013 ESTIMATED TIME...431 PM EDT MAXIMUM EF-SCALE RATING...EF0 ESTIMATED MAXIMUM WIND SPEED...85 MPH MAXIMUM PATH WIDTH...50 YARDS PATH LENGTH...0.25 MILES BEGINNING LAT/LON...42.10N / 71.10W ENDING LAT/LON...42.10N / 71.10W * FATALITIES...0 * INJURIES...0 * THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO CHANGE PENDING FINAL REVIEW OF THE EVENT(S) AND PUBLICATION IN NWS STORM DATA. ..SUMMARY THE NATIONAL WEATHER SERVICE IN TAUNTON MA HAS CONFIRMED A BRIEF TORNADO TOUCHDOWN IN STOUGHTON MA ON MAY 9 2013. THE TORNADO TOUCHED DOWN AT A CAR DEALERSHIP ON ROUTE 138 WHERE IT WAS CAPTURED BY A SECURITY CAMERA AND RECORDED ON CELL PHONE CAMERAS BY SEVERAL OF THE DEALERSHIP EMPLOYEES. THREE RV TRAILERS...WEIGHING ABOUT 5000 POUNDS EACH...WERE PUSHED BACK ABOUT 6 FEET AGAINST A CHAIN LINK FENCE. ONE TRAILER WAS LIFTED ABOUT 15 FEET INTO A LIGHT POLE BUT LANDED ON ITS WHEELS WITH MINIMAL DAMAGE. AN ALUMINUM DOOR ABOUT 20 FEET HIGH AND 15 FEET WIDE WAS BLOWN OUT OF THE SERVICE GARAGE. EYEWITNESSES REPORTED CEILING TILES BEING LIFTED INSIDE THE DEALERSHIP AS THE TORNADO PASSED OVERHEAD. THE TORNADO ENTERED A WOODED AREA JUST TO THE NORTHEAST OF THE DEALERSHIP. ABOUT 0.25 MILES AWAY...TWO LARGE PINE TREES WERE DOWNED ON ERICA DRIVE AND DEAN ROAD BEFORE IT DISSIPATED. BASED UPON A SURVEY OF THE DAMAGE...THE TORNADO IS CLASSIFIED AS EF0 ON THE ENHANCED FUJITA SCALE WITH MAXIMUM WINDS OF 85 MPH. THE PATH LENGTH WAS 0.25 MILES AND THE MAXIMUM WIDTH WAS ABOUT 50 YARDS. Here's a look at radar imagery about a half hour before the time of the tornado: The Supercell Composite Parameter was relatively low, although some slightly higher values did target the area near the tornado touchdown: The only severe weather report in the Northeast on Thursday was that tornado in Massachusetts!

Quincy

Quincy

 

Severe WX Outlook, NE, Mid-Atl.: Saturday, May 11th

As a cold front moves towards the East Coast on Saturday, some thunderstorm development is possible during the afternoon and early evening hours. Low threat (Conditions are somewhat favorable for severe thunderstorms) Mid-Atlantic region (east of Appalachians), lower Hudson Valley and SW New England. Conditions will destabilize in a warm, somewhat moist air-mass before an approaching cold front swings from west to east through the area. The biggest question mark is how much daytime heating will take place. Across Virginia, there will likely be more heating and with higher dew-points here as well, in the mid-60's, some thunderstorm development is likely. Some of these storms could reach severe limits. Further north, across eastern Pennsylvania, interior New Jersey, southeastern New York, northwestern Connecticut and the Berkshires, the threat of severe thunderstorm activity relies heavily upon daytime heating. The NAM continues to show some scattered showers and mid-level moisture limiting the destabilization process. With that said, the SREF/NAM/GFS still show a narrow finger of somewhat unstable air in this region. CAPE values between 250-500 J/kg, LI values around -2 and bulk shear around 30kt could result in a few thunderstorms reaching severe limits. Dew-points are progged to reach the lower 60's by the NAM. The 18z NAM simulated radar shows a squall line developing from Baltimore to Philadelphia to Poughkeepsie. However, this line is relatively short-lived as it collapses upon reaching the coastal plain and western Connecticut. It should be noted that helicity values increase towards the northeast, especially in New England. This may work to offset the slightly less unstable atmosphere. Bottom line, some thunderstorms may produce damaging winds from the mid-Atlantic region into southwestern New England. Some hail is possible here, but there's a stronger potential for severe hail further south. The tornado risk is relatively low, although Significant Tornado Parameter (STP) values indicate that a brief tornado or two could form anywhere in the yellow shading. Local topography across the Appalachians could aid in some rotation with any cells. When running the numbers, the tornado parameters are a bit below the mean tornado environments for historic tornadoes in the region, but are higher than what verified on Thursday with the brief EF-0 tornado in eastern Massachusetts. A few renegade thunderstorm cells could fire ahead of a cold front Saturday afternoon, especially across Virginia, where there may be a few supercells. A squall line along the cold front is more likely, advancing through eastern Pennsylvania early in the afternoon and towards the NYC metropolitan area and the coastal plain by mid to late afternoon. Instability will be key in the formation of and ability of this line to maintain itself. Marginal threat (Conditions are marginally favorable for severe thunderstorms) Mid and upper Appalachians and portions of southern New England. Shower and thunderstorm activity is likely across the entire area, but less daytime heating will limit the severe weather threat. As one moves eastward, especially towards the coastal plain of New England, the threat decreases significantly. Threat definitions...(Severe thunderstorm = wind gusts to 58 MPH and/or >1" hail) Marginal: Conditions are marginally favorable for severe thunderstorms. Low: Conditions are somewhat favorable for severe thunderstorms. Moderate: Conditions are moderately favorable for severe thunderstorms. High: Conditions are very favorable for severe thunderstorms. Extreme: Conditions are extremely favorable and dangerous thunderstorms are likely. *Disclaimer* The intent here is somewhat different than SPC severe weather outlooks. The green, yellow, etc. shadings do not directly correlate between SPC and my own outlooks. I'm still getting a feel for these outlooks, but I imagine that in more impressive severe setups, I will use red and orange colors a bit more generously than SPC might. Also, green colors on my maps indicate a marginal severe weather threat, while on SPC it corresponds to a general thunderstorm (not necessarily severe) threat.

Quincy

Quincy

 

April Forecast Verification for Inland Connecticut

I've been creating daily 6-day forecasts for the better part of this year, with a focus on inland Connecticut. Before making any forecast, I take a close look at the computer model forecasts through Day 6, including a few forecast techniques to see how verification pans out. In April, I had 29 days worth of data, out of a possible 30, to measure forecast accuracy. As expected, forecast error generally increases with time. It is interesting to note a spike at Day 5 and a decrease at Day 6. That goes back to two particular days that had poor Day 5 forecasts vs. actual temperatures. The spread is relatively uniform as well. The error with the NAM model does seem to increase faster with time than the others, which is not a surprise. DGEX data was used for Days 5 and 6. With respect to my own forecasts, I measure verification as a mean of inland temperatures across the state. When I look at the computer models, I choose Meriden (KMMK) as a central point. This is due to its location near the center of the state. With that said, since my own verification is slightly different than the control (KMMK), this may skew results slightly. For that reason, I will be creating 6-day forecasts specifically for Meriden as a go-forward. The Euro and MAV MOS rank fairly close, but it is very interesting to note that the negative (cold) bias the Euro has is almost a mirror reflection of the MAV MOS positive (warm) bias: The MAV MOS appears to correct some of its bias towards Days 5 and 6. That can perhaps be partially explained by the fact that MOS is skewed towards climatological temperatures. The NAM also seems to have somewhat of a cool bias. I re-project highs from the NAM for Day 1, but that re-projection seems to over compensate the bias, at least in the case of April. Explaining the models/forecasts... Q: My forecast high temperatures for inland Connecticut. (mean of inland stations) MAV MOS: Forecast high temperatures for KMMK. (06z model run) ECMWF: Forecast grid-point high temperatures for KMMK. (00z model run) NAMDGEX: Approximate high temperatures for KMMK. These values are interpolated off of a graphical forecast, so the numbers are estimated. I use the NAM for Days 1-4 and the DGEX for Days 5 and 6. (06z model runs) 850mb: An 850mb forecast technique that I have been working on for quite some time. Because this technique is based off of Danbury (KDXR), that station is used for verification. LAMP MOS: Forecast high temperatures for KMMK. (most recent run in morning) NAM Re-projection: This takes into account the actual 9 a.m. temperature vs. the 06z forecast for 9 a.m. for KMMK. That error is then re-projected into the high temperature forecast. Example: If the 9 a.m. temperature was 2°F warmer than forecast, then 2°F is added to the high temperature forecast. Consensus: A mean of each forecast above, including my previous forecast (continuity) How accurate was a Euro/MAV MOS blend? Well, not only do the opposing biases balance out close to zero, but the overall forecast error was less than any other forecast technique for Days 2-6: It's pretty interesting to see the results. It goes beyond comparing computer model verification. In order to become a better forecaster, I want to see what forecasts have worked out, which ones haven't and if I have any biases. This is only one month's worth of data, so more will need to be compiled over the long-run to see how models perform. I also expect that different models/techniques will perform differently depending on the season, weather pattern, etc.

Quincy

Quincy

 

Severe WX Outlook, NE, Mid-Atl.: Wednesday, April 24th

A cold front is forecast to move from west to east across the East Coast on Wednesday. The result could mean scattered thunderstorms along the front, along with a few severe thunderstorms. (Marginal threat) Middle Appalachians into DE, PA, inland NJ and interior NY. A similar setup to this past Friday is expected on Wednesday, with a cold front moving across the area during the afternoon and evening hours. The only difference here is that the cold front is not as strong as that scenario (last Friday) and less convective activity is expected. Ahead of the cold front, some marginal destabilization is expected as near-surface temperatures rise into the 70's, slightly steepening lapse rates. As a result, Lifted Index values between 0 and -2 are forecast. MUCAPE is meager, with values generally less than 500 J/Kg. Although dew-points are forecast to be in the mid to upper 50's, wind shear and helicity is forecast to be somewhat less than the last event. Bulk shear of 30 to 50kt is forecast across eastern Pennsylvania, coupled with storm relative helicity values of 100-200, so some isolated damaging wind gusts are possible. (Low threat) Interior Virginia, Central Maryland and portions of eastern Pennsylvania. In this region, the timing of the cold front corresponds closely with the peak daytime heating. There's also a sliver of 500 to 1000 J/Kg CAPE values expected in south-central Pennsylvania, down into Maryland and Virginia. It's also in this general area that there is a marginal tornado threat, however the tornadic setup on Wednesday is also less impressive than it was last Friday. Graphics to differentiate between the damaging wind and tornado threats: (No appreciable severe weather threat) Southern New England, Long Island and coastal plain of New Jersey. The cold front does not make it into this area until midnight or a few hours afterward. At that time, moisture is very limited, wind shear values relax and there should be little to no instability to fuel thunderstorm activity. Threat definitions...(Severe thunderstorm = wind gusts to 58 MPH and/or >1" hail) Marginal: Conditions are marginally favorable for severe thunderstorms. Low: Conditions are somewhat favorable for severe thunderstorms. Moderate: Conditions are moderately favorable for severe thunderstorms. High: Conditions are very favorable for severe thunderstorms. Extreme: Conditions are extremely favorable and dangerous thunderstorms are likely. As the spring season goes forward, I will be making more severe weather outlooks. Any feedback is appreciated and I am still working on the outlook/threat scale. I would like to compare forecasts to verification in the future, so some thought will be needed to address just how best to do so. *Disclaimer* The intent here is somewhat different than SPC severe weather outlooks. The green, yellow, etc. shadings do not directly correlate between SPC and my own outlooks. I'm still getting a feel for these outlooks, but I imagine that in more impressive severe setups, I will use red and orange colors a bit more generously than SPC might. Also, green colors on my maps indicate a marginal severe weather threat, while on SPC it corresponds to a general thunderstorm (not necessarily severe) threat.

Quincy

Quincy

 

Recap: Tornado in New York, April 19th, 2013

The National Weather Service (NWS) confirmed that an EF-1 tornado touched down in New York state Friday evening, shortly before 8 p.m. A strong cold front moved across Pennsylvania and New York state late Friday evening. At the same time, a marginally unstable air-mass was in place closer to the surface. With moderate to strong wind shear in place and significant storm relative helicity in place, the stage was set for damaging winds and even a marginal tornado threat. As a result, a Tornado Watch for a large portion of Pennsylvania and New York state. A tornado touched down near Bainbridge, N.Y. in Chenango County and stayed on the ground for 3.2 miles. The tornado was a strong EF-1 with maximum sustained winds of 110 MPH. Looking back at historical tornado environments in the same general area, the wind shear and helicity values in place on Friday were actually more "severe" than the climatological mean for past tornadoes. The only thing that was lacking was instability, as there was very little in place. Despite this fact, strong, twisting and turning winds aloft combined with an approaching squall line ahead of a cold front resulted in the tornado. PUBLIC INFORMATION STATEMENT...UPDATED NATIONAL WEATHER SERVICE BINGHAMTON, NY 954 AM EDT MON APR 22 2013 ...TORNADO CONFIRMED FROM 4 SSE BAINBRIDGE IN CHENANGO COUNTY TO 3 S SIDNEY IN DELAWARE COUNTY NEW YORK... UPDATED DATA ON LAT/LON POINTS AND WIDTH. LOCATION... FROM 4 SSE BAINBRIDGE IN CHENANGO COUNTY TO 3 S SIDNEY IN DELAWARE COUNTY NEW YORK DATE...APRIL 19 2013 ESTIMATED TIME...753 PM TO 758 PM EDT MAXIMUM EF-SCALE RATING...EF1 ESTIMATED MAXIMUM WIND SPEED...110 MPH MAXIMUM PATH WIDTH...200 YARDS YARDS PATH LENGTH...3.2 MILES BEGINNING LAT/LON...42.2481N / 75.4516W ENDING LAT/LON...42.2674N / 75.3939W * FATALITIES...0 * INJURIES...0 * THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO CHANGE PENDING FINAL REVIEW OF THE EVENT(S) AND PUBLICATION IN NWS STORM DATA. ..SUMMARY THE NATIONAL WEATHER SERVICE IN BINGHAMTON, NY HAS CONFIRMED THAT A TORNADO TOUCHED DOWN ABOUT 4 MILES SSE OF BAINBRIDGE IN CHENANGO COUNTY...TRACKED NORTHEAST ABOUT 3.2 MILES...AND THEN ENDED ABOUT 3 MILES SOUTH OF SIDNEY IN DELAWARE COUNTY NEW YORK FROM 753 PM EDT TO 758 PM EDT ON APRIL 19 2013. THE TORNADO TOUCHED DOWN BETWEEN INTERSTATE 88 AND HIGHWAY 206...ON EAST AFTON ROAD...WHERE 2 POWER POLES WERE SNAPPED AND A CAR WAS DESTROYED BY A LARGE TREE BRANCH. ANOTHER VEHICLE WAS ALSO DAMAGED. SEVERAL TREES WERE SNAPPED OR UPROOTED. A BARN HAD MINOR ROOF DAMAGE. THE TORNADO CONTINUED NORTHEAST AND CROSSED HIGHWAY 206...WHERE A FARM EQUIPMENT BUILDING AND A MOBILE HOME WERE HEAVILY DAMAGED...AND A STORAGE TRAILER WAS DESTROYED. OTHER NEARBY HOMES HAD MINOR DAMAGE...AND A CARPORT WAS LIFTED AND MOVED 75 FEETFARTHER DOWN ITS PATH...THE TORNADO INTENSIFIED TO A HIGH END EF1 STRENGTH WHILE TRAVELING IN THE VICINITY OF HOUCK DRIVE. IN THIS AREA IT UPROOTED OR SNAPPED MANY 1 TO 2 FOOT DIAMETER TREES ALONG ITS PATH...BOTH HARDWOODS /MAPLES/ AND SOFTWOODS /PINES/...WITH THE LARGEST MORE THAN 3 FEET WIDE. IT ALSO CAUSED STRUCTURAL DAMAGE TO A SINGLE FAMILY RESIDENCE AND GARAGE...WHILE TRANSPORTING A SIGNIFICANT AMOUNT OF DEBRIS A HUNDRED YARDS OR MORE. THE TORNADO THEN CROSSED INTO DELAWARE COUNTY...DOWNING SEVERAL MORE TREES ON SOME PROPERTIES ALONG HIGHWAY 8 BEFORE DISSIPATING. Here's an SPC archived radar image from 00z, just minutes after the tornado touched down. A noticeable kink can be seen along the squall line near the location of the tornado, along with the approximate track below it: Here are some more storm reports from Friday:

Quincy

Quincy

 

Updated: Severe WX Outlook, NE, Mid-Atl.: Friday, April 19th

A strong cold front approaches the Appalachians Friday afternoon and evening. Along that cold front, a squall line with thunderstorms is currently expected is develop. (Marginal threat) Middle Appalachians into Pennsylvania, northwestern New Jersey and interior New York: Daytime heating is expected to push temperatures into the low to mid-70's in the valley locations with mid to upper 60's in the higher elevations. Low and mid-level clouds will likely limit just how unstable the atmosphere can get. As a result, relatively low SBCAPE below 500 J/KG combined with near-zero or marginally negative Lifted Index values are expected. Despite strong winds aloft and effective bulk shear values increasing to 35 to 50kts along a cold front, the lack of instability will likely minimize the threat of severe weather. In addition, dew-points are forecast to stay in the 50's, perhaps coming close to 60° in Maryland and eastern Pennsylvania. However, a few isolated strong thunderstorms could develop Friday afternoon ahead of a cold front. There is a marginal threat of a few damaging wind gusts associated with a squall line along the cold front Friday afternoon into Friday night. (Low threat) Interior Virginia, east of the Appalachians: The atmosphere is likely to become slightly more unstable further south. SBCAPE values of 500 to 750 J/KG are forecast based off of SREF guidance. Lifted Index values as low as -3 combined with dew-points in the 60's and higher helicity values would support more strong to severe thunderstorm activity. Based off of this, there is a low threat of severe thunderstorms with damaging winds and large hail in this area. Some isolated thunderstorm cells are possible Friday afternoon, but locally severe storms could develop along a squall line Friday night as the cold front approaches. There is a marginal threat for an isolated tornado or two, but confidence in this potential is not particularly high at this point. (No appreciable severe weather threat) Connecticut (southern new England), NYC, Long Island and coastal plain of NJ/DE: With more of a marine influence allowing for less daytime heating, there is no appreciable threat of severe weather in these areas. Also, with the cold front not expected to move through until after midnight Friday (into early Saturday), this further implies that the severe weather threat is virtually non-existent. With that said, some locally strong wind gusts are possible as a decaying squall line and associated cold front moves through late Friday night into early Saturday morning. As the spring season goes forward, I will be making more severe weather outlooks. Any feedback is appreciated and I am still working on the outlook/threat scale. I would like to compare forecasts to verification in the future, so some thought will be needed to address just how best to do so. Learning is an ongoing process as I learned a lot about severe weather forecasting last spring/summer and there's still a lot more to cover. Experience also helps!

Quincy

Quincy

 

Severe WX Outlook, NE, Mid-Atl.: Friday, April 19th

A strong low pressure system is forecast to move up into the Great Lakes by Thursday and eventually into southeastern Canada late Friday into Saturday. A potent cold front associated with this storm will move towards the Appalachians by the second half of Friday. (For Wednesday and Thursday, severe thunderstorm activity is probable for the Mississippi Valley and portions of the western Ohio River Valley. I see a marginal setup for severe storms from Central N.Y. into the middle Appalachians. Even though a strong shortwave and upper level jet is expected to move into New York state and Pennsylvania, there are several factors which will likely limit the severe threat... With low-level moisture and clouds, daytime heating will not be maximized along the East Coast. Right now, the areas shown in green can expect gradually steepening lapse rates. However, dew-points are only expected to be in the mid-50's to around 60 north of Washington D.C., along with 2-meter temperatures in the mid-60's to lower 70's. eastern Pennsylvania and New Jersey could get well into the 70's, but with the front lagging further to the west, there really isn't much of a trigger to kick off any storms in that area. The SREF/NAM/GFS/Euro are actually fairly similar in timing and overall evolution of this storm system. Without much heating, relatively low CAPE values are forecast. The SPC SREF does show a ribbon of slightly negative (0 to -2) Lifted Index values from central Pennsylvania southward. This indicates a marginally unstable atmosphere. As one goes further south into Virginia, the severe weather indices increase, including dew-points into the 60's. This is why that area is outlined in a "low" threat potential. Wind shear values are a bit more supportive for severe weather, but even here, the storm system loses some of its punch as it reaches the Appalachian mountains. Effective bulk shear of 40-45kts is forecast across the region. Some strong winds aloft are expected with the front, but this area of stronger winds lags far enough back to really minimize the severe weather threat. Overall threats... -Damaging wind gusts could be supported anywhere in the green or yellow shadings. -In the yellow shading, there's a very slight risk of hail and isolated tornadoes. -In New England, gusty winds are possible with a band of rain and thunderstorms late Friday night into early Saturday, but damaging winds are not terribly likely. As the spring season goes forward, I will be making more severe weather outlooks. Any feedback is appreciated and I am still working on the outlook/threat scale. I would like to compare forecasts to verification in the future, so some thought will be needed to address just how best to do so. Learning is an ongoing process as I learned a lot about severe weather forecasting last spring/summer and there's still a lot more to cover. Experience also helps!

Quincy

Quincy

 

Virtual Storm Chase

There is a great competition called Virtual Storm Chase that has been given new life (for bragging rights only). This is the same competition that was started over on the old wxchat forums several years ago (mid 2000s). For those that do not know what it is, I have a attached a PDF copy of the rules below. It is a great learning experience for those interested in severe weather forecasting and a great way for even meteorologists to keep sharp. http://virtualstormchase.info The site "appears" to be broke ... but once you register (free) and login it works. Rules: Rules _ VirtualStormChase.pdf

thunderman

thunderman

 

Update On Severe Weather Threat Next Week

Not much has changed. It is starting to look as if the warm sector will continue East in active form. Could see a multi day severe weather outbreak from the Plains to the Ohio Valley/dixie alley. People in KS, OK, MO, and AR really need to be paying attention to this. Original blog post on this: http://www.americanwx.com/bb/index.php/blog/8/entry-95-early-week-plains-severe-threat/

thunderman

thunderman

 

Early Week Plains Severe Threat

Looks to be a significant severe weather threat early next week. An area of low pressure is expected to develop and move off the Rockies … as usual with upper level energy approaching/crossing the Rockies. Ahead of this system, there will be an extended period of northward return flow off the Gulf of Mexico … setting the stage for a moist and unstable boundary layer as our system moves in around Monday. A dry line will develop across Western parts of Kansas, Oklahoma, and Texas. As the dryline moves East, forcing (dryline and upper trough) looks to become sufficient for the development of thunderstorms within moderate to large instability and long/open hodographs. If things hold, would likely be a moderate or high risk day from SPC … with violent/strong long track tornadoes possible across parts of Oklahoma and Kansas.

thunderman

thunderman

 

Current Evolution of the QBO and Implications on the Atlantic Hurricane Season

To start, here's the equatorial zonal wind anomalies so far this spring. Can see the -QBO holding on by its thumbs, with the westerlies starting to descend and near 30mb (first days with a + anomaly since July 2011 WOW) The current profile fits the 330 degree phase of my "index" pretty well. Descending westerlies above 30mb, easterlies centered around 70mb, and neutral right around 30mb. The phase I would be keying in on for hurricane season based on average "residence time" is 60 degrees. Here's the tropopause pressure correlation for phase 60. It's a pretty weak signal, with on average zero correlation in the MDR and negative in the central Atlantic. This may support more disturbances in the central Atlantic more recurvatures of any TCs that do form. (Negative = a higher tropopause height, Positive = a lower tropopause height) Here's the same map for phase 90. Notice the equator to off-equator dipole tightens and intensifies, and the Gulf and NW Caribbean is under a very low correlation (high tropopause height) and that band extends across the Atlantic between 15N and 30N. That dipole that I mention is tightest and most intense around phase 120. So if the QBO reaches phase 90 during the season (essentially a full-blown +QBO), this suggests an increased TC threat in the NW Caribbean and Gulf. Of course this is one factor, and probably still relatively insignificant, but something that's interesting to discuss anyway

OKpowdah

OKpowdah

 

Light to Moderate Snow to Continue Through Into At Least Early Evening Hourse

Light ... to at times moderate ... snow will continue into the evening hours, as the upper level low moves slowly Eastward. Despite the snow, accumulations have been tough to come by thanks to a combination of above freezing temperatures and the late March sun angle. However, as we move closer to sunset, the snow will accumulate easier (much like we saw yesterday evening) and we could see up to another inch I think in some places. Some slick spots could develop as well later this evening on roadways.

thunderman

thunderman

 

Mid-Atlantic Snow forecast For March 24-25 (Initial)

The DC-Baltimore-Philly areas are expected to miss out on the more significant accumulations yet again as bothersome low-level temperatures above freezing and March climo. rear their ugly heads. One of the saving graces with this event is the onset of snow will be overnight, though this did not really help the I-95 corridor and points east during the last event back in the first week of March. Surface temperatures will generally be above freezing in the lower elevations, so these areas will need good rates to make up for it. A large chunk of the precipitation is expected during the daytime hours, where we will have the March Sun to contend with in addition to the temperatures. Higher elevations that stay at or below freezing will fare much better with accumulation. Forecast confidence is normal to slightly below normal.

Ellinwood

Ellinwood

 

Palm Sunday - Monday (3/24-25/13) Threat

While still being a day 5ish event, it is not to early to start looking at some of the possible implications of various models. At this juncture, we generally have the GFS and the Euro book-ending a possibilities window that includes a cutter to Chicago and a more suppressed system that goes East of Hatteras For the most part been consistently left of the GFS ... with its ensembles a tad to the right of the operational Euro (but no where near the GFS). The 12z GFS Ensembles cut the difference with somewhat of a middle ground ... bringing the primary low into Ohio, with a coastal transfer. Depending on the amount of moisture return that is achieved in the warm sector, the operational GFS could be a notable severe weather event. And would keep QPF amounts across the DC/NOVA area on the light side with little possibilities for winter weather. The transfer with this solution simply happens too late to provide the lift for precipitation and wraparound of cold air. Then we have the Euro with it's more southern solution. It would mean a smaller spatial window for severe weather possibilities and a better chance for wintry weather for the area (especially west ... like we saw with the early March event). Given the time range and the placement of the the ensembles in the middle of the operationals I would expect to see some compromise towards the middle in terms of track over the next 1-3 days ... rather than an extreme on either side verifying. If I had to pick a solution verbatim from this mornings 12z suite for the heck of it, it would be the GEFS.

thunderman

thunderman

 

Connecticut Snowfall Totals: Mar. 7-8, 2013

Here are some maps that I compiled from various sources. Most of the reports came in through the National Weather Service, with a few from this forum and social media reports that passed through quality control. Snowfall amounts were greatest across the higher terrain of Tolland County. This was due to a persistent band of moderate to heavy snow, as well as the altitude as temperatures were marginal through a portion of the event. Totals in the Connecticut River valley and the immediate shoreline were generally lower than surrounding areas. If any amounts you reported conflict with these amounts, please comment back with your total(s). Here is an alternate black and white version of the map:

Quincy

Quincy

 

Final Snow Forecast: 2 Maps, Mar. 6-8

I don't really expect much snowfall at all tonight. For some continuity and a slight amount of uncertainty, I painted the entire area with 2" or less of snow. Eastern Conn. and northern R.I. have perhaps a 50/50 shot at 1-2": of snow, while the rest of the area has a high probability of receiving less than 1". Temperatures and moisture look very marginal and although some precipitation should back southern sections of southern New England, I don't see it being a big deal. There may be a few slushy roads for the Thursday morning commute. I don't think it's fair to make a total snowfall map for both events. The coastal plain should rise several degrees above freezing during the day on Thursday with most inland areas also cracking 32F. Also, western areas that may see no accumulation at all tonight could easily end up with some of the higher amounts tomorrow night. The snow Thursday night into Friday morning ("Round 2") looks a bit more significant. It gets tricky nailing down enhanced snow along an inverted trough across eastern N.Y. and western New England. At the same time, precipitation closer to a center of low pressure well south of Cape Cod may bring a period of snow to northeastern Conn., northern R.I. and interior eastern Mass. Here, it's a big question mark where totals could verify either low or high. The computer models are having issues nailing down precipitation totals, while some say widespread amounts over 6" could be realized in my eastern 3-6" zone. I don't see it happening, but take that for what it's worth. The confidence for the latter forecast is only moderate, but this will be my last snowfall map for the period. Confidence is higher for the first round.

Quincy

Quincy

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